1.备份原镜像文件
cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2.下载新的CentOS源
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
*若系统是最小化安装时会提示没有wget需安装wget
yum -y install wget
3.生成缓存
yum makecache
原文:https://www.cnblogs.com/dukun166/p/12094805.html